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- Dochev, Dimitar Milkov, 1981, et al.
(författare)
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The influence of aging and annealing on the properties of Nb/Al-AlOx/Nb tunnel junctions
- 2010
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Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 234:4
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Konferensbidrag (refereegranskat)abstract
- This paper presents results of our studies on aging and annealing properties of Nb/Al-AlOx/Nb junctions. We performed a long room temperature aging with subsequent annealing at different temperatures up to 250°C. A distinct change of the junctions' normal-state resistance has been observed. Aging at room temperature results in a slight decrease of the normal-state resistance combined with improved junction quality, characterised by a better subgap-to-normal resistance ratio. Annealing at moderate temperatures in air increases the normal-state resistance and leads to improvement of the junction quality followed by degradation at higher annealing temperatures. The increase in the junction quality after long-term aging at room temperature is attributed to relaxation of the internal junction structure and interfaces, thus, resulting in a lower density of interface traps. The deterioration at higher annealing temperatures could be a consequence of diffusion processes at the Al/Nb interface. We observe a sufficiently clear difference between the behaviour of preliminary aged and newly fabricated junctions after annealing: for the aged high-quality junction, the degradation was negligible up to temperatures of 200°C, while non-aged junctions show a much faster and abrupt degradation at lower annealing temperatures.
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| 4. |
- Zhao Ternehäll, Huan, 1982, et al.
(författare)
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Effect of buffer design on structural and electrical properties of InAs films grown on GaAs substrates
- 2014
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Ingår i: the 41st international symposium on compound semiconductors, Montepillier, France.
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Konferensbidrag (refereegranskat)abstract
- Different buffer structures were grown by molecular beam epitaxy (MBE) to accommodate the large lattice mismatch of InAs with GaAs substrate. A novel graded digital superlattice (GDSL) buffer design was proposed and compared with the common one-step buffer and linear alloy graded (LAG) buffer designs. Effect of buffer structures on structural and electrical properties of the InAs films was investigated. High quality InAs films were obtained on GaAs substrates.
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| 5. |
- Zhao Ternehäll, Huan, 1982, et al.
(författare)
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Effect of Buffer Quality on the Performance of InAs/AlSb Heterostructure Backward Tunneling Diode
- 2014
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Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035.
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Konferensbidrag (refereegranskat)abstract
- InAs/AlSb Heterostructure Backward Tunneling Diodes (HBTDs) were grown on semi-insulating GaAs (100) substrate using molecular beam epitaxy (MBE). The current-voltage characteristics of the InAs/AlSb HBTDs, both at room temperatures (RT) and cryogenic temperatures, have been studied as a function of the InAs buffer thickness. It has been found that a thicker InAs buffer doesn’t improve the surface roughness but decreases the threading dislocation (TD) density, thus a higher curvature coefficient in the current-voltage characteristics near zero-bias is obtained.
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